Vasectomies and Prostate Cancer. Refer to the vasectomy/ prostate cancer study discussed in Example 1.5 on page 6.

(a). How could the study be modified to make it a designed experiment?

(b). Comment on the feasibility of the designed experiment that you described in part (a).

The given statement is:

Refer to the vasectomy/ prostate cancer study discussed in Example 1.5 on page 6.

We can identify a large number of men who are ready for vasectomy to convert an observational study on vasectomies and prostate cancer into an experimental study (say 20,000 men). Then select another 20,000 men who will not have their vasectomy.

The other group should be similar to the first, with the exception that it will not undergo vasectomy. Then count the number of men who developed prostate cancer in the first group who had a vasectomy and the second group who hadn't, and compare the two groups' results to see if the study is low because of the vast number of men involved.

The feasibility of such an experiment, as well as the fact that the number of men who get prostate cancer following vasectomy is extremely low.